The present invention relates to a pneumatically actuated switching device, and more particularly, to an improved construction and arrangement of parts to form an enlarged pneumatic bulb with a sloping and ultra sensitive tactility for delivering a quantity of pressurized air sufficient to actuate an electrical switch in a nurse call system.
Pneumatic bulbs such as disclosed in U.S. Pat. Nos. 3,823,285 and 5,155,309 are used to generate a volume of pressurized air sufficient to operate an electrical switching circuit in a nurse call system. A system of this type is particularly useful in environments where it is undesirable to use a conventional electrical switch because of a possible catastrophic explosion when an exposed switching circuit operates in an atmosphere containing a high concentration of a potentially explosive gas. Such an atmosphere commonly occurs in hospital, nursing and assisted living facilities due to a patient's use of oxygen. A patient actuated call system is particularly needed in facilities where there is a need or desire by a person to summon for help, particularly, when a patient is in a weakened or disabled condition. Most hospitals and health care institutions today have signaling systems by which in each patient area a patient may initiate a signal that is received by a station or at an allocated substation within a larger area to summon assistance. Typically, for example, in a hospital a select group of patient areas is serviced by a given nurse station where calls for assistance by patients are taken. Most patient areas must accommodate the use of oxygen even if it is only on an emergency basis whereby electrical switches commonly used in other industries cannot be utilized. A need, however, exists for a pneumatic bulb construction that is well suited for the environment of use particularly in a patient environment where the patient has severely restricted mobility capabilities and therefore must assume that the pneumatic device will remain in place without random or uncontrolled movement. For example, a pneumatic bulb illustrated in U.S. Pat. No. 3,823,285 has hemispherical end parts adjoined with a cylindrical mid-section. The cylindrical configuration of the pneumatic bulb and patient movement result in the fundamental instability of the bulb on a flat surface and cannot be relied upon to remain in a fixed or desired location on a patient's mattress. A more recent construction of a pneumatic bulb is disclosed in U.S. Pat. No. 5,155,309 and uses a base plate to provide a broad area of support for a peripheral rim and a center post of an actuator dome. The base plate has protrusions on the support surface to allow the bulb to remain at a desired designated area with great reliability and integrity for operating a switching device. The dome resembles the appearance of a doughnut and the use of a center post to establish the defining configuration establishes to requirement for an elastic compression of the bulb that may exceed the capabilities of a patient having severely limited physical capabilities.
Examples of other known nurse call systems can be found in U.S. Pat. Nos. 4,702,443; 4,484,367; 4,298,863; and 3,781,843. In U.S. Pat. No. 4,702,443, a cord holding device is disclosed wherein a belt fastener is used to hold a base onto a mattress so that the base can in turn receive a cord-holding member. The cord-holding member supports a cord to allow limited movement of the cord the end of which carries a push button electric switch. In U.S. Pat. No. 4,484,367, a side rail of a patient's bed is wrapped with a flexible sheet having a pocket in one side of the sheet for receiving an electronic push button device serving as a call device for summoning a nurse. U.S. Pat. No. 4,298,863 discloses a patient call system in which a patient operated transducer is mounted on a patient's face or a portion of the body. The transducer is interconnected by pneumatic tubing to a pneumatically actuated switch that is part of an electronic monitoring system. U.S. Pat. No. 3,781,843 discloses a bed guard system in which the upper rail surfaces of patient restraining rails at opposite sides of a bed are fitted with a detector. Each detector is formed with an elongated rail engaging pocket shape to fit on the rail surface and an overlying elongated internal cavity extending generally the length of the rail. In internal cavity forms a site for a fluid material which can be pressurized by an applied pressure to the top surface of the rail covering.
Accordingly, it is an object of the present invention to provide a pneumatic actuator with an improved shape for patients access to an enlarged actuator dome providing a sloping ultra sensitive tactility for ease of use by all elderly or geriatric and convalescent care patients.
It is a further object of the present invention to provide a pneumatic bulb embodying a construction such that a wedge shaped base has an upstanding support wall to an elliptically shaped actuator dome with an enlarged surface area so as to minimize the effort required to pressurize a volume of air needed to operate a call system for summing assistance or help.
It is another object of the present invention to provide a pneumatic bulb embodying an elasticity and volume enclosed by the pneumatic bulb such that it makes it much easer for a patient with limited physical capabilities to activate pneumatic bulb by brushing against it with an area of the cheek or head and could be placed almost any where that motion can be directed to activate a call for assistance.